System for controlling the transfer of materials into or out of a reservoir



Nov. 10, 1970 -r. c. COVILL- 3,539,313

SYSTEM FOR CONTROLLING THE TRANSFER OF MATERIALS INTO OR OUT OF ARESERVOIR Filed July 19, 1968 2 Sheets-Sheet 1 NOV. 1,1970 1-. c, cov3,539,818

SYSTEM FOR CONTROLLING THE TRANSFER OF MATERIALS v v INTO OR OUT OF ARESERVOIR Filed July 19, 1968 2 Sheets-Sheet 2 FIG. 2.

US. Cl. 307-9 9 Claims ABSTRACT OF THE DISCLOSURE A system forcontrolling the transfer of material into or out of a mobile reservoirsuch as a fuel tank. A switch device associated with an electricalcircuit interrupts said circuit when the amount of material in thereservoir falls outside a selected limit. The reservoir may becompartmentalized into a plurality of horizontally separatedcompartments which are separately controlled by the same electricalcircuit.

The present invention relates to a system for controlling the transferof material into or out of a reservoir for gases, liquids or particulatesolids, and is particularly concerned with a means for filling and/oremptying the reservoir wherein the reservoir and the filling and/oremptying means are movable relative to each other.

It is often required during the filling and/or emptying of a reservoirthat the amount of material stored in the reservoir should fall withinone or more particular limits: i.e., the amount of material in thereservoir should not exceed a specified maximum quantity and/or shouldnot fall below a specified minimum quantity. Common examples Where oneor more of these requirements are to be met in the filling and/ oremptying of road tankers and marine tankers.

The present invention seeks to provide a system for ensuring that themaximum and/r minimum amount of material stored in the reservoir isautomatically controlled.

The system in accordance with this invention comprises a switch deviceassociated with the reservoir, fixedly located transfer means operablefor transferring material into or out of the reservoir, and means fordetachably interconnecting the switch device and the transfer means toform a circuit, the switch device being arranged to interrupt thecircuit when the amount of material in the reservoir falls outside aselected limit, and the transfer means being operable only when thecircuit is complete.

The circuit may be arranged for transmitting electrical, pneumatic orhydraulic signals.

Preferably, a part of the circuit when completed, provides a connectionto earth from the reservoir. This is advantageous where the material tobe transferred is inflammable since any accumulated static charge due tofriction in the material can be discharged with substantially no risk offire or explosion from this cause. Conveniently, the connection to earthmay be through the fixedly-located part of the circuit so that theinterconnection of the switch device and the transfer means concurrentlyearths the reservoir, and provides a definite indication that thereservoir is earthed. In the case where the circuit transmits electricalsignals, the voltage and circuit would be, of course, quite small. Theelectrical energy may be supplied in the form of direct current or ofalternating current, or rectified alternating current.

The transfer means may include a valve and/or a pump for the transfer ofmaterial, and a relay which United States Patent 0 3,539,818 PatentedNov. 10, 1970 operates when the circuit is complete to provide power, inoperation, for the valve and/or pump.

The switch device may operate in accordance with either the level or theweight of material in the reservoir.

The invention also includes an installation comprising at least onereservoir in combination with the system as described in the precedingparagraphs.

There may be a plurality of reservoirs in the installa-' tion, therebeing a switch device for each reservoir, and the devices being allconnected.

Preferably, the or each device is mounted on the, or a respective,reservoir.

The invention will now be described by Way of nonlimitative example onlyand with reference to the accompanying drawings, in which:

FIG. 1 depicts diagrammatically one form of an installationincorporating a system in accordance with the invention.

FIG. 2 illustrates a part of the installation of FIG. 1 to a greaterscale.

FIG. 3 illustrates another part of the installation of FIG. 1 to agreater scale, and

FIG. 4 depicts an alternative part which may be used in place of thepart shown in FIG. 2.

Referring first to FIG. 1, the installation generally indicated byreference numeral 10, comprises a reservoir or tank 11 forming thecargo-carrying part of a mobile road tanker 12 suitable for transportinga liquid such as petroleum spirit, or a dry, particulate solid such assugar or flour. The tank 11 is divided into a number of horizontallyseparated compartments Ila-11c, each of which is required to be filledwith cargo to a specified level.

Each compartment 11a-11e is provided with an electrical switch 13a-13erespectively which is responsive to the level of cargo in thecorresponding compartment. The switches 1311-1312 are electricallyconnected in series by conducting wires 14. When the level of cargo in acompartment is below a specified maximum level, the switch 13 for thatcompartment is closed. If the specified maximum level in a compartmentis exceeded, the corresponding switch is open.

It will be appreciated that when the maximum level of cargo for eachcompartment 11a-11e is not exceeded, all the switches 13a-13e will beclosed and will form an uninterrupted electrical path. As depicted inFIG. 1, the specified maximum level of cargo in compartment He has beenexceeded and switch 13e is open, thus interrupting the electrical path.

The switches 13a-13e are connected to a fixedly located intrinsicallysafe source of electrical energy generally indicated by reference 15,via a two pole detachable connecting plug 16 which is adapted to engageelectrically with suitable contacts connected respectively to switch 13aand switch 13c. (An intrinsically safe source is a source which iscertified by Her Majestys Factory Inspectorate of the Ministry of Labouras being incapable of producing sparks of sufficient energy to ignitestored materials or vapours emanating therefrom.) In this case, thesource 15 comprises a step-down transformer 15a which is connected to analternating mains supply 15b of 240 volts, and has a low-voltage outputof, say 15 volts alternating current. The transformer output isconnected to two contacts of a full-wave rectifier 15c and the two othercon tacts of the rectifier are connected respectively to a highohmic-valve resistor 15d, and the connecting plug 16. The source 15 thusprovides full-wave rectified alternating current at 15 volts and a lowcurrent. The current may be of the order of 20 milliamps when thecircuit is complete and functioning correctly.

A relay 17 is provided in series with the resistor 15d of source 15. Therelay 17 serves to control the supply of electrical power to a fixedlylocated solenoid valve 18 for regulating the flow of cargo through afilling pipe 19 and a flexible filling hose (not shown) for transferringcargo into a desired compartment 11a11e.

The arrangement is such that when current flows through the relay 17,the relay 17 provides a path for electrical power to pass via lines and21 to the valve 1 8. The valve 18 opens enabling cargo to pass throughpipe 19 and the flexible hose (not shown) to the required compartment11a-11e. This situation will result only when all of the switches13a-13e are closed, i.e'. the specified maximum level of cargo for everycompartment 11a- He has not been exceeded and when the detachableconnecting plug 16 is in the position shown.

When the current through the relay 17 is interrupted, e.g. due toexceeding the specified cargo level in one of the compartments 11a-11e,or because the connecting plug 16 is not attached in itselectrically-connecting location-the relay.-- 17 interrupts theelectrical conduction path in line 20 causing the solenoid valve 18 tobecome inactivated and to close the passage for cargo in pipe 19. Thus,two conditions must be fulfilled in order that cargo can flow throughpipe 19; these conditions are that the connecting plug 16 must beconnected and that the maximum specified level of cargo in every one ofthe compartments 11a-11e must not have been exceeded.

In many instances, the movement of the cargo either in the tank 11 orthrough the pipe 19 generates static electrical charges which can behazardous if allowed to accumulate. This is particularly the case whenthe cargo is inflammable, e.g. petroleum spirit, sugar or flour. In theembodiment of the invention depicted in FIG. 1, any static chargesassociated with the road tanker 12 are discharged to earth through anearthing strap 23 attached to one of the leads from the source 15. Forconvenience, it is preferred to arrange the earthing strap 23 as part ofthe fixedly-located part of the installation comprising, inter alia, thesource 15, the relay 17 and the solenoid valve 18.

In the arrangement of FIG. 1, there is depicted a con necting plug 16asubstantially identical with the connecting plug 16 but at a differentlocation on the road tanker 12. The connecting plug 160: is connectedinto the aforedescribed electrical circuit in parallel with plug 16, butso that it functions in the same manner as plug 16 and may be used as analternative thereto to suit the convenience of the operating personnel.Preferably, only one at a time of the plugs 16, 16a is employed, thechoice being determined to suit the convenience of the personnelinvolved, The connecting electrical conductors are indicated by thedotted lines 14a.

, It is to be noted that the system in accordance with the invention isfail safe. That is to say that any break in the electrical connectionswill cause the solenoid valve 18 to become inoperative so that theloading operation is interrupted until the break is remedied.

The regulation of the quantity of material transferred into or out ofeach compartment of the tank 11 maybe effected by suitable measuringdevices (not shown) upstream of the solenoid valve 18. If thesemeasuring devices, or their control systems, break down, the system ofthe invention inactivates the material transfer system, thus avoidingtroublesome, expensive or dangerous spillages of cargo. For example,during the filling of a road tanker with a measured quantity ofpetroleum, the tank of the tanker may initially contain some residualpetroleum from its previous duty, and there will not be suflicient roomin the tank to accomodate the measured quantity; in such circumstances,the system of the invention will prevent any overfilling of the tank andthe consequential spillages. Alternatively, the system of the inventionmay be employed to regulate the transfer of material in the absence ofother measuring devices.

FIG. 2 shows in greater detail a preferred form of switch which may beused as one of the switches l3a-13e, particularly for liquid cargoes.

The switch, generally designated by reference 25 comprises a flexiblediaphragm 26 of polytetrafiuoroethylene exposed to the cargo space ofthe tank 11 via an electrically-insulating tube 27 of nylon orunplasticised polyvinyl chloride extending downwardly to just below thedesired maximum height of cargo, and a micro-switch 28 having contacts(not shown) which are in electrical contact when the level of cargo inthe tank is less than the desired maximum level (corresponding with theswitches 13a-13d of FIG. 1) and which become separated in a mannerhereinafter explained when the desired maximum level in the tank isexceeded (corresponding with switch 13e of FIG. ,1). The microswitch 28has an operating arm 29 which is biassed to an inoperative position by aspring 30, the compression in the spring 30 being adjustable by anadjusting nut 31.

When the cargo in a compartment 11a-11e approaches the desired maximumlevel, it closes ofif the lower end of the tube, trapping air and/orvapour therein. If the level of the cargo continues to rise, the trappedair and/or vapour is compressed and the rise in pressure moves thediaphragm upwardly so that it pushes upwardly against an actuatingmember 32. The actuating member 32 is displayed upwardly into contactwith the operating arm 29 which then is moved upwards to cause thecontacts in the microswitch 25 to separate, so that the electricalcircuit is interrupted. The effect of this interruption has already beenexplained by reference to the switches 13a-13e of 'FIG. 1. When thelevel of the cargo falls, the pressure in the tube 27 falls andeventually the corresponding movement of the diaphragm permits themicroswitch to complete the electrical circuit.

Pressure switches are advantageous in that no electrical conductors needenter the cargo compartments Ila-11a.

Since the parts of the pressure switch which are exposed to the interiorof the tank 11 (the tube and the diaphragm) are electricallynon-conductive, the risk that static changes accumulating in the tank 11will be discharged outside the tank 11 is almost negligible.

FIG. 4 shows in detail another form of switch which may be used in placeof the switch shown in FIG. 2. This switch comprises two rigidelectrical conductors a, 50 which are retained in a tube 51 extendingdownwardly from a retaining nut 52. The nut 52 retains the tube 51 and aconnection housing 53 against the top of the tank 11. About half-waydown the outside of the tube 51 is a fixed annular washer 54, and withinthe tube, just below the level of the washer 54, is a springy metalcontact 55a which is supported by the conductor 50a, and extendsdownwardly therefrom and somewhat inwardly towards a similar springymetal contact 55b supported by the conductor 50. Both of the contacts55a, 55b are of magnetisable metal, such as steel.

An annular float 56 of spongy polyvinyl chloride is arranged to travelup and down around the tube 51 when the surface of the cargo has risenabove the floats lowest position as determined by an adjustable annularwasher 57 resting on a cotter pin 58 extending through the tube 51.

Recessed into the top of the float 56 is an annular magnet 59.

When the level of the cargo is so high that the float 56 is disposedadjacent the Washer 54, and with the magnet 59 substantially surroundingthe contacts 55a, 55b, the contacts are outwardly attracted away from ech other by the annular magnet 59.

While the contacts 55a, 55b are touching, under the action of theirinherent springiness, they provide an electrical path through the switchfrom the lead 14 on one side of the switch to the lead 14 on the otherside thereof, in correspondence with the switches 13a-13d of FIG. 1.When the contacts 55a, 5512 are separated by the attraction of theannular magnet 59, the electrical path through the switch isinterrupted, as in the case with the switch 1312 of FIG. 1. If the levelof the cargo should fall so that the float moves downwardly away fromthe washer 54, the contacts 55a, 55b will spring back into theirmutually contacting position thus providing an uninterrupted electricalpath through the switch.

The invention may take forms other than that described for example,where the cargo is a particulate solid, it may be preferred to replacethe above-described forms of switch by other means, such as a proximityprobe. This latter comprises, in effect, a condenser including adownwardly protruding conductive electrode concentrically surrounded byan annular electrode. The cargo is able to rise into the space betweenthe two electrodes thus increasing the capacitance of the condenser.When the capacitance attains a selected value, the circuit including theproximity probe is interrupted by a switch.

In another form, the switches 13a-13e may be replaced by meansresponsive to the weight of the cargo, e.g. strain gauges. When aselected weight of cargo is exceeded, the circuit is interrupted.

The invention may be modified for operations involving the discharge ofcargo from tank 11. In this case, the switches 13a-13e, pressureswitches float-operated switches, proximity probes or strain gauges areadapted to interrupt the electrical circuit when a specified minimumquantity of cargo remains in the tank 11 or a compartment thereof.

Various combinations of the features disclosed above may be employedwithout departing from the invention as defined by the appended claims.

What is claimed is:

1. A system for controlling the transfer of material into or out of amobile reservoir comprising:

(a) a reservoir;

(b) a spring biased diaphragm switch disposed in said reservoir,responsive to the level in said reservoir;

(c) a fixedly-located transfer means operable for transferring materialinto said reservoir; and

(d) means for detachably interconnecting said diaphragm switch and saidtransfer means to form a circuit which is interrupted by said diaphragmvalve when the amount of material insaid reservoir falls outside aselected limit thereby cutting off operation of said transfer means.

2. The system of claim 1 including a means for grounding said electricalcircuit connected to said transfer means.

3. The system of claim 1 wherein said diaphragm switch comprises:

(a) an electrically insulated tube extending into said reservoir;

(b) an actuating member disposed inside said insulating tube, responsiveto the level of material in said reservoir;

(c) an operating arm, responsive to said actuating 55 member, disposedabove and in communication with said actuating member;

((1) a microswitch disposed above said actuating member, and incommunication with said operating arm;

(e) a spring means connected to said actuating member and said operatingarm, which biases said arm so that said switch is normally closed.

4. A system for controlling the transfer of material into or out of amobile reservoir comprising:

(a) a reservoir;

(b) a switch comprising a magnetic activating means responsive to thelevel in said reservoir;

(c) a fixedly located transfer means operable for transferring materialinto said reservoir; and

(d) means for detachably interconnecting said switch and said transfermeans to form a circuit, which is interrupted by said switch when theamount of material in the reservoir falls outside a selected limit,thereby cutting off operation of said transfer means.

5. The system of claim 4 including a means for grounding said circuit.

6. The system of claim 4 wherein said switch comprises:

(a) a tube, provided with a pair of annular constraints around said tubeat two vertical levels, disposed in said reservoir;

(b) a pair of electrical conductors connected to said circuit anddisposed in said tube, each of the ends of said conductors tipped with amagnetizable metal contact, said contact biased to touch each otherbelow said upper annular constraint;

(c) a magnetized float disposed around said tube between saidconstraints providing the means for opening said circuit when said floatreaches the level of said touching contacts.

7. A system for controlling the transfer of material into or out of areservoir comprising:

(a) a reservoir comprising a plurality of horizontally separatedcompartments;

(b) a plurality of series connected switch devices, one said devicedisposed in each of said compartments;

() a fixedly-located transfer means operable for transferring materialinto any of said compartments;

((1) means for detachably interconnecting said plurality of switchdevices and said transfer means to form a circuit which is interruptedwhen the amount of material in any of said compartments falls outside aselected limit, thereby cutting off operation of said transfer means.

8. The system of claim 7 wherein each of said switch devices comprisesan actuating member responsive to the level of material in saidcompartment, disposed inside a tube, said actuating member activating anoperating arm to disengage a microswitch, whereby said circuit isinterrupted.

9. The system of claim 7 wherein said switch device comprises amagnetized float responsive to the level of material in saidcompartment, disposed around the tube in which a pair of electricalconductors, electrically connected to said circuit, are disposed withtheir ends in electrical communication by means of a pair ofmagnetizable metal contacts, whereby said float acts to break thecircuit when the level in said compartment moves said float up to thepoint where said conductors are in electrical communication.

References Cited UNITED STATES PATENTS 2,380,884 7/1945 Von Stoeser etal 222-64 3,170,479 2/1965 Mueller 22264 X 3,339,578 9/1967 Smith 307118X 0 FOREIGN PATENTS 938,473 2/ 195 6 Germany.

ROBERT K. SCHAEFER, Primary Examiner 5 T. B. I OIKE, Assistant ExaminerUS. Cl. X.R.

